Common rail injection systems working at very high injection pressures are being increasingly used for supplying internal combustion engines with fuel. In these common rail injection systems, fuel is pumped with the aid of a high-pressure pump into a high-pressure common rail, from which the fuel is injected into the combustion chambers of the internal combustion engine using injectors. In particular, for diesel engines, injectors having an injection valve which is opened and closed hydraulically by a servo valve are used to establish the time sequence of the injection operation into the combustion chamber. In this case, the servo valve is actuated by a magnetic or piezoelectric actuator. Legislation on emissions, which is becoming increasingly strict worldwide, and the constant increase in the efficiency of engines result, in the case of these common rail systems, in a larger number of partial injections being required for each injection operation, i.e., for each operating cycle of the internal combustion engine, the quantity of fuel of the individual injection becoming smaller and smaller, and the variance of the injection quantities between multiple injection operations, i.e., operating cycles, having increasingly strict tolerances. This also represents new challenges for the methods and devices for injector testing.